This invention relates to a leaf spring constraining apparatus, more particularly to an apparatus for constraining leaves of a leaf spring or laminated spring, which constrains a leaf, cambered in the previous step, in the directions of the thickness and width thereof to effectively prevent possible strain which occurs when the cambered leaf is hardened or quenched by immersing it in an oil.
Suspension systems consisting of a plurality of leaves 10 which are laminated and bound as shown in FIG. 11 are suitably employed in land transportation vehicles such as railway cars and trucks. Each of the leaves 10 can be prepared, for example, after formation of an eye at one end portion or each end portion of a rolled plate blank having a predetermined thickness or a taper at the other end portion thereof, by subjecting the thus processed blank, which is heated entirely, to a cambering treatment so as to be provided with a predetermined camber. The camber to be imparted to the blank varies depending on the application and load stress: a type in which the camber angle gradually diminishes or increases from the center toward each end and a type in which the middle portion has no camber. The thus cambered blank 10 is quenched by immersing it in a quenching oil contained in an oil tank.
There is a serious problem when the cambered blank or leaf 10 is quenched in that the leaf undergoes distortion during cooling thereof if it is quenched by immersing it in the oil in a free state with no constraint. If the leaf 10 is distorted particularly in the direction of the thickness thereof, the camber profile itself will be changed, and thus the leaf 10 cannot be used as a normal product. Under such circumstances, it is attempted to immerse the leaf 10 having a camber into the quenching oil while the leaf 10 is constrained in the direction of the thickness thereof so as to prevent such distortion concomitantly occurring with cooling.
As described above, the distortion which affects the camber profile of the leaf 10 can be controlled by constraining the leaf 10 in the direction of the thickness thereof when it is quenched. However, since the leaf 10 is not constrained in the direction of the width thereof, there remains a possibility that the leaf 10 undergoes distortion in said direction. It should be noted here that the distortion in the direction of the width of the leaf 10 does not affect the camber profile, so that the leaves 10 which underwent such widthwise distortion can be treated by operators to correct such distortion after quenching and used as normal products.
However, since the degree of widthwise distortion varies depending on the leaves 10, it requires the skill of an expert to correct such distortion into a specified tolerable range. Namely, intricate and time-consuming correcting procedures were required after the quenching treatment, leading to reduction in the productivity of leaves 10, disadvantageously.